This invention relates to a disposable diaper having a high ventilation property.
A disposable diaper described in Japanese Utility Model Application Disclosure Gazette (Kokai) No. Sho64-18105 includes a pair of air-permeable and liquid-resistant barrier flaps formed on a pair of transversely opposite side flaps so as to elastically extend in a longitudinal direction of the diaper.
Japanese Patent Publication Gazette (Kokai) No. Hei4-55072 discloses a method for making a backsheet used in a disposable diaper, particularly to obtain such backsheet made of an air-permeable and liquid-impermeable plastic film.
In these Gazettes, the term xe2x80x9cair-permeable and liquid-resistantxe2x80x9d and the term xe2x80x9cair-permeable and liquid-impermeablexe2x80x9d are synonymously used. These known techniques may be adopted to improve a ventilation property of the foregoing barrier flaps and portions of a diaper backsheet in the proximity of the barrier flaps intended to surround the wearer""s legs and thereby to alleviate undesirable stuffiness during use of the diaper.
The diaper proposed by the above-mentioned techniques will necessarily enlarge a diameter of each aperture formed in the barrier flaps and/or the backsheet in order to improve the air-permeability in these barrier flaps and/or backsheet. However, such measure may cause the desirable liquid-impermeability required for the barrier flaps and/or the backsheet. In other words, the conventional techniques have an antimonic relationship between improvement of the air-permeability and improvement of the liquid-impermeability.
In view of the problem as has been described above, it is an object of the invention to provide a disposable diaper having both a relatively high air-permeability and a relatively high liquid-impermeability.
The present invention provides a disposable diaper, comprising a liquid-permeable topsheet, a liquid-impermeable backsheet and a liquid-absorbent core disposed therebetween so as to form a front waist region, a rear waist region and a crotch region extending therebetween, and further comprising longitudinally opposite front and rear end flaps and transversely opposite side flaps which are formed by the topsheet and the backsheet extending outward from peripheral edges of the absorbent core, a pair of barrier cuffs being elastically extendable in a longitudinal direction of the diaper and being bonded, in an extended condition, to an inner surface of an associated one of the side flaps. Each of the barrier cuffs has longitudinally opposite front and rear ends, and inner and outer side edges extending in parallel to each other between the front and rear ends. The front and rear ends of each of the barrier cuffs are respectively bonded to the front and rear end flaps. Each of the barrier cuffs has, in the crotch region, the outer side edge bonded to the associated side flap and the inner side edge bonding to the associated side flap along a line defined between the outer side edge and an associated edge of the absorbent core. Each of the barrier cuffs has, in a transverse cross-sectional view and in the crotch region: a first wall section formed with a plurality of elastic members and which first wall section extends inwardly from the outer side edge of the barrier cuff, an outermost one of the elastic members being spaced and distinct from the bonding of the outer side edge of the barrier cuff and the associated side flap, and a second wall section intersecting the first wall section inwardly of an innermost one of the elastic members and extending downward to the inner side edge of the barrier cuff. A dimension of the first wall section in a transverse direction thereof is larger than that of the second wall section in the transverse direction. The first and second wall sections, together with a portion of the associated side flap defined between the outer and inner side edges, describe a hollow space of a substantially triangular shape, under contraction of the barrier cuff in the longitudinal direction. Portions of the barrier cuffs and the side flaps participating in the formation of the triangular hollow spaces are air-permeable.
According to a preferred embodiment of the invention, elastic members are bonded, in an extended condition, in the longitudinal direction of the diaper, to each of the barrier cuffs in a zone thereof extending between the outer and inner side edges thereof rather adjacent the outer side edge thereof and thereby the barrier cuff is made elastically stretchable in the longitudinal direction of the diaper.
According to another preferred embodiment of the invention, the barrier cuffs and the side flaps are made of an air-permeable and liquid-impermeable material.
According to still another preferred embodiment of the invention, each of the barrier cuffs has a dimension between the outer and inner side edges thereof being 1.2xcx9c2.0 times of a dimension of the side flap similarly between the outer and inner side edges thereof.
The disposable diaper according to the invention is characterized by a unique arrangement such that leak of body fluids can be double-blocked by the pair of barriers cuffs and the pair of side flaps at least in the crotch region of the longitudinal three regions, i.e., the front waist region, the rear waist region and the crotch region extending between the former two regions. This arrangement allows the air-permeability to be adjusted to relatively high levels in barrier cuff as well as in the side flaps. Each hollow space defined in the crotch region by each barrier cuff and the side flap associated with this barrier cuff has its inner volume which is variable depending on a movement of the diaper. More specifically, vapor-containing air staying within the diaper is expelled to the exterior of the diaper or dry air is sucked from the exterior into the diaper depending on the movement of the diaper. In this manner, a problem of stuffiness from which the wearer would suffer can be effectively solved.
The present invention also provides a disposable diaper comprising a liquid-permeable topsheet, a liquid-impermeable backsheet and a liquid-absorbent core disposed therebetween so as to form a front waist region, a rear waist region and a crotch region extending therebetween, and further comprising longitudinally opposite front and rear end flaps and transversely opposite side flaps which are formed by both the topsheet and the backsheet extending outward from peripheral edges of the absorbent core, a pair of barrier cuffs being elastically extendable in a longitudinal direction of the diaper and being bonded, in an extended condition, to an inner surface of an associated one of the side flaps. Each of the barrier cuffs has longitudinally opposite front and rear ends, and inner and outer side edges extending in parallel to each other between the front and rear ends, the front and rear ends of each of the barrier cuffs being respectively bonded to the front and rear end flaps. Each of the barrier cuffs has, in the crotch region, the outer side edge bonded to the associated side flap and the inner side edge bonded to the associated side flap in between the outer side edge and an associated edge o the absorbent core. Each of the barrier cuffs has a dimension between the outer and inner side edges selected to be larger than a dimension of the associated side flap between the outer and inner side edges of each of the barrier cuffs so that a contraction of each the barrier cuff in the longitudinal direction of the diaper causes an inner surface of each the barrier cuff to be spaced from an inner sur ace of the associated side flap at least in the crotch region and thereby forms a hollow space between each the barrier cuff and the associated side flap. Portions of the barrier cuffs and the associated side flaps participating in the formation of the hollow spaces are air-permeable. The outer side edge of each of the barrier cuffs, in the crotch region, is directly bonded to the topsheet in the associated side flap along a line where the topsheet and the backsheet are bonded together.
In accordance with an aspect of the present invention, the topsheet extends to the outer side edge of the barrier cuff.
In accordance with another aspect of the present invention, the extension stress of the innermost elastic member is less than that of the outermost elastic member.
In accordance with a further aspect of the present invention, the extension stress of the middle elastic member(s) is less that that of the innermost elastic member.
In accordance with yet another aspect of the present invention, the permeability of the backsheet in the hollow space is higher than in the remainder thereof.
Still other objects and advantages of the present invention will become readily apparent to those skilled in the art from the following detailed description, wherein the preferred embodiments of the invention are shown and described, simply by way of illustration of the best mode contemplated of carrying out the invention. As will be realized, the invention is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, all without departing from the invention. Accordingly, the drawings and description thereof are to be regarded as illustrative in nature, and not as restrictive.